Suction roll scavenging means



Dec. 8, 1964 ELY SUCTION ROLL SCAVENGING MEANS Filed July 30, 1962INVENTOR. Dona/a A. E/y

BY 2%. a

ATTORNEYS 3,160,553 SUCTIGN RGLL ESCAVENGENG MEANS Bonaid A. Ely,Beioit, Wis assignor to Beloit (lei-porntion, Beloit, Win, a corporationof Wisconsin Filed July 3%, 1962, Ser. No. 213,312 4 (Ilaims. {CL162-274} The present invention relates to improvements in paper machinesand more particularly to an improved mecha nism for removing water froma rotating roll such as a perforated suction roll.

In various locations on paper machines drilled suction rolls areemployed and the holes in the roll receive water in the performance oftheir appointed function in the machine. This water must be removedduring rotation. An example is the suction roll in a press nip wherein adrilled suction roll is used, and the holes receive water in the nip andsome water collects on the surface of the roll which must be removedfrom the roll at a location after the nip so that the holes and surfaceare clear before again entering the nip.

It has heretofore been proposed to use such items as foils or scrapersin nip defining relationship with the suction roll to remove the excesswater therefrom. The scrapers or foils tend to force water into theholes as it is removed from the land areas between the holes. Anotherproposed method is to use a pressure gland within the suction roll shellto blow the remaining water out of the suction shell holes. The pressuregland removes the water from the holes but tends to ignore the landarea. A combination of the two is impractical, and other methodsemployed have met with disadvantages.

It is accordingly an object of the present invention to provide animproved mechanism for removing water from the rotating roll whichreceives water during operation.

A further object of the invention is to provide an improved mechanismfor the effective removal of water from both the openings and the landareas tncrebetween of a perforate suction roll.

A feature of the invention is the provision of a suction roll scavengingmeans for a rotatable perforate roll receiving liquid during operationhaving a scavenging roll in close running relation to the perforate rollsuch as to form a narrow gap of uniform width therebetween forming ascavenging nip, and driving the scavenging roll in an opposite directionof rotation than the perforate roll so that the surfaces at the niptravel in the same direction, and preferably driving the scavenging rollat a higher surface speed and employing a relatively small scavengingroll so that water is effectively removed from the openings in theperforate roll and from the surface thereof. A saveall enclosure isprovided enclosing the major portion of the perforate roll and thescavenging roll for receiving the removed water.

Other objects, advantages and features will become more apparent withthe teachings of the principles of the invention in connection with thedisclosure of the preferred embodiment thereof in the specification,claims and drawings, in which:

FIGURE 1 is a schematic front elevational view shown partially insection and taken from the end of a section of a paper machine having asuction roll scavenging means constructed and operating in accordancewith the principles of the present invention;

FIGURE 2 is a schematic fragmentary side elevational view showinganother arrangement; and

FIGURE 3 is a schematic fragmentary front elevational view similar toFIGURE 1 illustrating a further arrangement.

As shown on the drawings:

The features of the invention are illustrated as being embodied in a tworoll press couple. The press con- United States Patent f 3,15%,553Patented Dec. 8, 1984 sists of a plain top roll 1 and a perforatedrilled suction roll 2 which is in the form of a shell. A suction box 3is provided within the shell having suitable suction and drainage meansof conventional design, which need not be shown.

The press rolls 1 and 2 define a press nip N therebetween through whichruns a press felt 4 supporting a paper web 5. The press felt 4 issupported on guide rolls 6 and 7 and is formed in a loop.

As is known from conventional operation, as the web 5 and the felt 4pass through the nip N water is pressed from the web 5 into the felt,and the suction box 3 draws water from the felt into the drilledperforations 4. Some water is of course thrown off of the surface of theroll 2 by a centrifugal action but a certain amount adheres to thesurface and is retained within the holes in the roll 2 due to surfacetension. The water which is thrown off is gathered by a saveallenclosure it? provided with suitable drainage means.

Positioned adjacent the surface of the roll 2 after it leaves the pressnip N is a scavenging roll 8. The scavenging roll is shown as positionedbeneath the perforate roll 2 and forms a scavenging nip N therewith. Thescavenging roll 8 is driven by a suitable drive means illustrated in theform of a motor J, preferably at a higher surface speed than theperforate roll 2. On the oifgoing side of the nip N the suction roll isevacuated from air and water on its circumference and within the holes.The water is sucked from within the holes and the surface of theperforate roll 2 and is thrown out outwardly as illustrated to be caughtby the saveall pan 10.

The scavenging roll is positioned parallel to the perforate roll 2 andpreferably is positioned to obtain a narrow gap between the scavengingroll 8 and the suction roll 2. The nip opening or gap is uniform alongthe length of the rolls for a uniform water removal effect.

In some structures the suction roll is heavily crowned, as illustratedin FIGURE 2 by the suction roll 12. In such event, a scavenging roll 13may be used which is formed with a concave surface to form a nip N ofuniform width.

Another method of operation is to slightly force the scavenging roll 8against the suction roll 2, as illustrated in FIGURE 3. Suitablepressure applying means shown schematically at 11 may be employed sothat the nip N is closed. The water film on the surface of the suctionroll is adequate to provide for the necessary lubricant. In the eventthat a closed nip is used as illustrated in FIGURE 3, the scavengingroll 8 may be of the Mount Hope type. In each of the arrangements ofFIGURES 1, 2 and 3, with an open nip such as shown in FIGURES 1 and 2,or closed nip such as shown in FIGURE 3, the scavenging roll ismaintained in what may be termed close running relationship with thesurface of the suction roll 2 to provide an effective removal of waterfrom the holes and from the surface of the suction roll.

In summary, in the present arrangement a high speed rotating scavengingroll is provided positioned in close running relation to the roll to bedewatered, and in driving the scavenging roll at a high speed asubstantial vacuum at the outgoing side of the nip is provided whicheffectively removes the water and throws it into the surrounding saveallpan 10.

While the use of the mechanism has been described in connection with asuction press roll, it will be understood that the principles of theinvention may be applied to any roll in a paper machine which isconstantly in contact with Water. For example the invention may beemployed with a suction couch roll on a Fourdrinier, or to a plain orsuction breast roll. Suction rolls of felt presses may also econstructed in accordance with the principles described.

The drawings and specification present a detailed disclosure of thepreferred embodiments of the invention, and it is to be understood thatthe invention is not limited to the specific forms disclosed, but coversall modifications, changes and alternative constructions and methodsfalling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a roll assembly including a rotatable roll having water receivingrecesses in the surface receiving water during operation, a rollscavenging means comprising, a scavenging roll parallel to saidrotatable roll and in close running relation thereto forming ascavenging nip therebetween, and drive means separate from the rotatableroll positively driving said scavenging roll in a rotational directionopposite to the rotatable roll at a positive periph eral speedindependent of the speed of the rotatable roll so that the surfaces willtravel in the same direction in the nip.

2. In a roll assembly including a rotatable roll having water receivingrecesses in the surface receiving water during operation, a rollscavenging means comprising, a scavenging roll in close running relationto the rotatable roll and forming a scavenging nip therebetween, anddrive means separate from the rotatable roll for driving said scavengingroll at a faster peripheral speed than the rotatable roll and in arotational direction opposite to the rotatable roll so that the surfaceswill travel in the same direction in the nip.

3. In a roll assembly including a rotatable roll having water receivingrecesses in the surface receiving water during operation, a rollscavenging means comprising, a scavenging roll parallel to saidrotatable roll and spaced therefrom to form a narrow gap of uniformWidth therebetween forming a scavenging nip, and drive means separatefrom the rotatable roll for driving said scavenging roll in a rotationaldirection opposite to the rotatable roll so that the surfaces willtravel in the same direction in the 4. In a press comprising a pair ofpress rolls forming a nip therebetween for receiving a felt carrying apaper web, one of said rolls having water receiving recesses, thecombination comprising, a scavenging roll in close running relation tothe recessed roll and forming a scavenging nip therebetween, drive meansseparate from the recessed roll for driving said scavenging roll at afaster peripheral speed than the recessed roll and in a rotationaldirection opposite to the recessed roll so that the surfaces will travelin the same direction in the nip, and a saveall enclosure enclosing thescavenging roll and a major portion of the recessed roll for receivingand draining liquid removed from the recessed roll.

References Cited in the file of this patent UNITED STATES PATENTS1,934,543 Johnson Nov. 7, 1933

1. IN A ROLL ASSEMBLY INCLUDING A ROTATABLE ROLL HAVING WATER RECEIVINGRECESSES IN THE SURFACERECEIVING WATER DURING OPERATION, A ROLLSCAVENGING MEANS COMPRISING, A SCAVENGING ROLL PARALLEL TO SAIDROTATABLE ROLL AND IN CLOSE RUNNING RELATION THERETO FORMING ASCAVENGING NIP THEREBETWEEN, AND DRIVE MEANS SEPARATE FROM THE ROTATABLEROLL POSITIVELY DRIVING SAID SCAVENGING ROLL IN A ROTATIONAL DIRECTIONOPPOSITE TO THE ROTATABLE ROLL AT A POSITIVE PERIPHERAL SPEEDINDEPENDENT OF THE SPEED OF THE ROTATABLE ROLL SO THAT THE SURFACES WILLTRAVEL IN THE SAME DIRECTION IN THE NIP.